Presentation on theme: "* How did exercise affect your heart rate? Why do you think this happened? * How does your heart rate affect the rate at which red blood cells travel."— Presentation transcript:
* How did exercise affect your heart rate? Why do you think this happened? * How does your heart rate affect the rate at which red blood cells travel throughout your body? * Did your heart rate return to normal (or almost normal) after you rested? Why or why not?
The cardiovascular system has three types of blood vessels: * Arteries (and arterioles) – carry blood away from the heart * Capillaries – where nutrient and gas exchange occur * Veins (and venules) – carry blood toward the heart.
* Arteries and arterioles take blood away from the heart. * The largest artery is the aorta. * The middle layer of an artery wall consists of smooth muscle that can constrict to regulate blood flow and blood pressure. * Arterioles can constrict or dilate, changing blood pressure.
* Capillaries have walls only one cell thick to allow exchange of gases and nutrients with tissue fluid. * Capillary beds are present in all regions of the body but not all capillary beds are open at the same time.
* Venules drain blood from capillaries, then join to form veins that take blood to the heart. * Veins have much less smooth muscle and connective tissue than arteries. * Veins often have valves that prevent the backward flow of blood when closed.
* The heart is a cone-shaped, muscular organ located between the lungs behind the sternum. 100,800 beats per day With every beat, about 70mL of blood is pumped out of the heart!!
* The heart muscle forms the myocardium, with tightly interconnect cells of cardiac muscle tissue. The pericardium is the outer membranous sac with lubricating fluid.
* Four chambers: two upper, thin-walled atria, two lower, thick-walled ventricles. * The septum is a wall dividing the right and left sides.
* Each heartbeat is called a cardiac cycle. * When the heart beats, the two atria contract together, then the two ventricles contract; then the whole heart relaxes. * Systole is the contraction of heart chambers * Diastole is their relaxation.
* The cardiovascular system includes two circuits: 1) Pulmonary circuit which circulates blood through the lungs, and 2) Systemic circuit which circulates blood to the rest of the body. 3) Both circuits are vital to homeostasis.
* Cardiovascular disease (CVD) is the leading cause of death in Western countries. * Modern research efforts have improved diagnosis, treatment, and prevention. * Major cardiovascular disorders include atherosclerosis, stroke, heart attack, aneurysm, and hypertension.
* Atherosclerosis is due to a build-up of fatty material (plaque), mainly cholesterol, under the inner lining of arteries. * The plaque can cause a thrombus (blood clot) to form.
* A cerebrovascular accident, or stroke, results when an embolus lodges in a cerebral blood vessel or a cerebral blood vessel bursts; a portion of the brain dies due to lack of oxygen. * A myocardial infarction, or heart attack, occurs when a portion of heart muscle dies due to lack of oxygen.
* Partial blockage of a coronary artery causes angina pectoris, or chest pain. * An aneurysm is a ballooning of a blood vessel, usually in the abdominal aorta or arteries leading to the brain. * Death results if the aneurysm is in a large vessel and the vessel bursts. * Atherosclerosis and hypertension weaken blood vessels over time, increasing the risk of aneurysm.
* Heart transplants are routinely performed but immunosuppressive drugs must be taken thereafter. * There is a shortage of human organ donors. * Work is currently underway to improve self-contained artificial hearts, and muscle cell transplants may someday be useful.